As many as eight to 10 people are believed trapped in the rubble of two buildings that collapsed in central Wednesday in central Philadelphia.
WPVI-TV reported that at least 10 people have been injured.
Emergency crews quickly closed off access to the site at 22nd and Market Streets and began frantically digging through piles of bricks and concrete.
Philly.com reported that one building apparently housed a Hoagie City shop on the first floor as well as apartment buildings.
The front of an adjacent building housing a Salvation Army thrift shop remained standing, but the back of the structure had collapsed.
Philly.com quoted Marc Newell, who was doing landscape work nearby,as saying the collapse created an "unbelievable rumble" like the sound of a freight train.
He said that he could hear "moaning" from the rubble and could tell immediatley that people were trapped inside.
The accident happened at 10:45 a.m. Wednesday. A building on the block has been under construction.